Use method constant_time_compare from oslo.utils
Use method constant_time_compare from oslo.utils

Oslo.utils provides same function constant_time_compare, so just use it.

Change-Id: I790a25c4bc28a2c10ff6fb2a2f356b12df98ca6b

stackforge/osprofiler,openstack/osprofiler,stackforge/osprofiler,openstack/osprofiler,openstack/osprofiler,stackforge/osprofiler